Full-spectrum passive communication system and method

Abstract

A passive communication system having devices with wide-band antenna circuits configured to receive ambient radiation and to use the energy therefrom to reflect a modulated signal, preferably using backscatter techniques, for writing and reading data to and from the devices in the system.

1. A communication device, comprising:
 a passive receiver coupled to first and second antennae to receive and reflect wide-band ambient radiation, the receiver configured to modulate the received ambient radiation to form a modulated signal and to transmit the modulated signal via backscatter transmission, the device further comprising a mixer to receive signals from the antennae and extract a modulated signal therefrom using energy from the ambient radiation. 
 
   
   
     2. A communication device, comprising:
 a passive receiver having a first wide-band antenna configured to receive ambient radiation, a second antenna configured to receive ambient radiation, a mixer having first and second inputs fed with respective outputs from the first and second antennas, the output from the second antenna delayed at the mixer with respect to the output from the first antenna for comparison and extraction of a modulated signal. 
 
   
   
     3. The device of  claim 2  wherein the first antenna has a first polarization and the second antenna has a second polarization. 
   
   
     4. The device of  claim 2  wherein the first and second antennas are identical and are pointed in the same direction. 
   
   
     5. The device of  claim 2  wherein the second antenna is configured to have directional selectivity to enhance detection of a modulated signal in the ambient radiation. 
   
   
     6. A communication device, comprising:
 a passive receiver having a wide-band antenna configured to receive ambient radiation and a circulator circuit configured to mimic input from a second antenna and a mixer configured to receive outputs from a second antenna and a mixer configured to receive outputs from the antenna and the circulator and to extract a modulated signal therefrom. 
 
   
   
     7. A communication system, comprising:
 a first passive receiver having an antenna and configured to receive ambient energy, to modulate the received ambient energy to form a modulated signal, and to transmit the modulated signal via backscatter transmission through the antenna; and 
 a second passive receiver having an antenna circuit configured to receive the ambient energy with the modulated signal, and to extract the modulated signal from the ambient energy. 
 
   
   
     8. The system of  claim 7  wherein the antenna circuit of the second passive receiver comprises a first antenna and a second antenna, the second antenna having directional selectivity to enhance reception and detection of the modulated signal. 
   
   
     9. The system of  claim 7  wherein the antenna circuit of the second passive receiver comprises a first polarized antenna and a second polarized antenna, the first polarized antenna having a polarization that is opposite to a polarization of the second antenna, and the antenna of the first passive receiver comprises a polarized antenna having the polarization of the second antenna of the second passive receiver. 
   
   
     10. The system of  claim 7  wherein the second passive receiver is configured to use CDMA to simultaneously decode multiple modulated signals received at the antenna circuit. 
   
   
     11. A communication system, comprising:
 a first passive device having a wide-band antenna circuit and configured to receive wide-band radio frequency radiation and to utilize energy from the received radio frequency radiation to reflect a modulated signal; and 
 a second passive device configured to receive the wide-band ambient energy and to extract the modulated signal therefrom. 
 
   
   
     12. The system of  claim 11  wherein the second passive device comprises first and second antennas coupled to a mixer, the second antenna coupled to the mixer via a delay circuit, the mixer configured to compare the signals received on the first and second antennas and to extract the modulated signal therefrom. 
   
   
     13. A communication method, comprising:
 receiving ambient radiation at a first passive device having a wide-band antenna circuit configured to receive and utilize the energy from the received ambient radiation to reflect a modulated signal via backscatter transmission; and 
 receiving at a second passive device the ambient radiation from a wide band of radio frequency transmissions; and 
 using the energy from the received ambient radiation to detect the modulated signal therein. 
 
   
   
     14. A communication method, comprising:
 receiving ambient radiation at a first passive device having a wide-band antenna circuit and utilizing the energy from the received radiation to reflect a modulated signal; 
 receiving at a second passive device the ambient radiation and the modulated signal and extracting the modulated signal therefrom using the energy from the received ambient radiation; and 
 using the energy received from the ambient radiation to generate a further modulated signal therefrom for backscatter transmission from the second passive device to the first passive device. 
 
   
   
     15. A full spectrum passive communication system, comprising:
 a first passive communication device comprising a passive modulation circuit coupled to a wide-band antenna and configured to receive ambient radiation and to reflect a modulated signal in response thereto; and 
 a second passive communication device comprising a detection circuit coupled to a first antenna circuit configured to receive ambient radiation and to a second antenna circuit configured to receive ambient radiation, the detection circuit configured to compare the signals received on the first and second antenna circuits to extract the modulated signal. 
 
   
   
     16. The system of  claim 15  wherein the detection circuit comprises a mixer coupled to the first and second antenna circuits and a delay circuit coupled between the mixer and the second antenna circuit. 
   
   
     17. The system of  claim 15  wherein the first and second antenna circuits are polarized to have opposite polarizations. 
   
   
     18. The system of  claim 15  wherein the wide-band antenna of the first passive communication device is polarized to match the polarization of one of the first and second antenna circuits of the second passive communication device. 
   
   
     19. The system of  claim 15  wherein the first and second antenna circuits are configured to have directional sensitivity.